UC Davis

Directed energy deposition (DED) is an additive manufacturing process which can be used to produce customized complicated parts with less cost compared with the conventional subtractive manufacturing method. However, the parts produced by DED can be deformed severely due to excessive heat accumulation. The input energy, typically laser and electron beam, is commonly regulated in many literatures to minimize the deformation based on the temperature information of the existing clad. Although the energy input control method is proved effective in reducing the deformation, the productivity of DED process is not increased. In this thesis, a feed rate-based fuzzy logic controller is proposed to maintain geometric consistency and increase the production rate at the same time. The geometric consistency and productivity are effectively improved, through numerical simulation and experiments of thin wall and square blocks in stainless steel 316L. However, feed rate control is not functional for small parts without sufficient cooling time. Therefore, a series of square blocks with various dimensions are modeled to test the threshold for choosing the proper control method. Additionally, a python program is developed to accelerate the simulation speed.